Right hemisphere lateralization and holistic processing do not always go together: An ERP investigation of a training study

Ricky Van-yip Tso, 1. Department of Psychology, The Education University of Hong Kong; 2. Psychological Assessment and Clinical Research Unit, Centre for Psychological Health, The Education University of Hong Kong

Hangyu Chen, Department of Psychology, The University of Hong Kong

Yui Andrew Yeung, Department of Psychology, The University of Hong Kong

Terry Kit-fong Au, Department of Psychology, The University of Hong Kong

Janet Hsiao, Department of Psychology, The University of Hong Kong

Abstract

Holistic processing (HP) and right-hemispheric lateralization both
mark expertise in visual object recognition such as face and sub-ordinate object
perception. However, counter-examples have been found recently: Experiences of
selective-attention-to-parts such as writing experiences in Chinese characters
reduced HP but increased right hemisphere lateralization. We investigated the
association between HP and brain activities measured by event-related potentials
(ERP) in participants trained to recognize artificially-created scripts using
either whole-word or grapheme-to-phoneme approaches. Stronger N170 activities
were found in both hemispheres in both training approaches. However, the two
training approaches induced correlations in opposite directions between HP and
the ERP signals in the right hemisphere: In the whole-word condition the HP
effect increased, whereas in the grapheme-to-phoneme condition the HP effect
decreased, with stronger right-hemispheric N170 activities. This demonstrates
that HP and right hemispheric lateralization are separate processes that are
likely associated with different perceptual mechanisms.